The Transmission Rebuilders Network

World-class transmission rebuilders from around the world interacting on transmission diagnostics and repair.
http://www.transbuilder.com/

Pre 1929 Vintage Chevrolet Transmissions

Provides instructions for teardown, inspection, repair and assembly of Pre WW-II Chevrolet Transmissions. Lists replacement part numbers, information on Johnson Overdrive and a source page listing over 30 dealers for all types of Chevrolet related items.
http://www.cybersurfers.net/~herb/gearbox.htm

A Short Course on Automatic Transmissions

Long article explaining the concepts behind modern automatic transmissions and their repair.
http://www.familycar.com/transmission.htm